The present invention relates to footwear and, more particularly, to a footwear construction and a method for making the same.
In the footwear industry, there is an ongoing effort to produce footwear including a cushioning system that provides a high level of comfort for wearers. The need to produce such a cushioning system is particularly pronounced in the design of work, walking and athletic footwear, where increased cushioning is a primary objective. For example, to minimize the effects of standing and walking on hard surfaces (e.g., concrete floors), it is desirable to provide footwear that cushions the wearer""s foot, particularly the heel, from the hard surface.
Many conventional cushioning systems are presently in use. In simple systems, a foam layer of varying thickness is either (1) adhered directly to an insole of a shoe before the shoe is assembled or (2) added as a footbed after the shoe is assembled. Another system incorporates a cushion disposed over the insole in a specific area, such as the heel, which typically experiences the most impact during walking. A problem with these systems, however, is that an increase in the size of the upper to accommodate the added cushion is required. This often results in a distorted looking upper or shoe, increased in size to accommodate the cushion, that is loose fitting.
One solution to these problems is disclosed in U.S. Pat. No. 6,145,220 to Johnson, Jr., which avoids adding bulky cushion layers by using a specialized heel plug or cushion disposed in a cavity perforated through shoe components in the heel area. The cavity is cut completely through the insole, midsole and outsole to accommodate the heel plug. The shank of the Johnson shoe also includes a hole corresponding to the cavity. This structure increases cushioning and maintains a low shoe profile, however, its manufacture is complicated and costly. To ensure that the different layers around the cavity remain intact, nails are used. The nails are positioned in a precise pattern to prevent them from extending into the heel cavity, where they may impede insertion of the heel plug into that cavity. After continued use, the nails holding the layers together also have a tendency to release, thereby allowing the layers to delaminate around the heel cavity. Additionally, each layer must be precisely sized and perforated to accommodate the heel plug. Furthermore, the heel plug of Johnson moves relative to the insole, the outsole and the heel of the shoe to add cushioning, but in some cases too much cushioning. As a result, the cushioning movement of the heel plug may reduce support in the shoe and make the shoe feel unstable.
Although the cushioning systems of the prior art provide cushioning, there remains a long felt and unmet need for an easily manufactured footwear construction that provides a desired level of cushioning over the life of the footwear.
The aforementioned problems are overcome in the present invention that provides an insole platform that is shaped to define an integral heel recess. A cushion insert including a heel cushion extending therefrom is disposed over the insole platform so that the heel cushion fits into and substantially fills the heel recess.
In another embodiment, the insole platform is shaped to define an integral recess in the forefoot portion, and the insert includes a corresponding sole cushion extending from it that fits into and substantially fills the sole recess. A transverse member, integral with the insole platform, separates the heel and sole recesses.
In a third embodiment, the insole platform includes a shank secured to the insole, around the heel recess. The shank preferably extends partially into the heel recess and across a portion of the transverse member to add rigidity and torsion strength to the insole platform and consequently the shoe. The shank also is preferably integrally attached to the insole platform as the insole platform is manufactured, for example, by insert molding. The shank preferably includes inclined shank walls, extending into the heel recess to center a wearer""s heel in the recess.
In another embodiment, the insole platform is secured to an upper with a rib extending from the insole platform. A welt is attached around the insole platform to the rib as well. A midsole is secured to the welt, and an outsole is further secured to the welt and midsole. The outsole includes upwardly opening recesses in the forefoot and heel portions. Cushion plugs may be separately manufactured and inserted in these recesses or may be molded directly in the outsole to provide additional cushioning.
A footwear assembly of the present invention is preferably manufactured using the general steps of (a) securing an insole platform to an upper, the insole platform being shaped to define a recess; (b) securing a midsole and/or an outsole to the undersurface of the insole platform; and (c) fitting a cushioning insert into the upper positioned over the insole platform, the insert including a cushion that fits in the corresponding recess in the insole platform.
The present invention provides a novel footwear construction including a low profile cushioning system. The interaction of the recessed insole platform with the cushion of the insert in the heel eliminates the need for a heel plug extending through the insole, midsole and outsole. Without a heel plug cavity, the need for precisely perforating and nailing multiple layers of the sole assembly around the cavity is obviated. Additionally, the stability and support of the footwear is uncompromised with the added cushion. Specifically, the heel cushion of the insert interfits directly in the heel recess of the insole to avoid movement relative to multiple components of the shoe. Furthermore, the integrally molded shank around the heel recess of the insole platform provides an exceptional, torsion-resistant platform to prevent lateral strain on the ankles of a wearer and improve the rigidity of the footwear. Moreover, footwear incorporating the insole platform may be assembled without securing together all the layers of the solexe2x80x94the insole, midsole, and outsolexe2x80x94with fasteners such as nails.
These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiments and the drawings.